I bought this in lieu of the more expensive Canon mk II or the original Canon IS 70-200. My copy is very sharp, focuses quickly (perhaps a hair slower than the Canons) and I prefer the color. (Sorry, it matters). I've been very pleased with it and the performance per dollar can't be beat.

I shoot with a Canon 60D and bought this lens mainly for shooting indoor Rodeo. It does an excellent job with the fast action of the Rodeo. My copy is very sharp and OS works like a charm. At more than haly the price of the new Canon and still lower than the older Canon 70-200 2.8 IS it's a real winner. Problems: None

Great telephoto, was lucky pick up a new copy rather cheap. Feels great, finally Sigma decided to drop the old finish. Optically its better then Mark I Canon, but worse then Mark II Canon. If you can Afford Canon 70-200 IS USM II go for that instead. OS is very reliable (so far) had to send it to Sigma once for AF repair because it stopped working (after 3 months of using it). That is one thing that you always have to keep in mind with third party lenses. Out of all the lenses I had, Sigma ...